Home | Reptile and Amphibian Health | feeding and diet | Thawing Frozen Mice and Rats for Snakes and Other Reptiles

Thawing Frozen Mice and Rats for Snakes and Other Reptiles

Frozen rodents are now widely available in the pet trade and, when used properly, are a safe food source that can save time, space and money. As opinions vary concerning proper thawing methods, I thought it might be useful to outline the procedures that are followed in major zoological parks.  Based on the human food guidelines set down by the US Department of Health and Human Services and the US Department of Agriculture, they have served me well throughout my career as a zookeeper and herpetologist.


General Considerations

There are two safe methods that can be used to defrost rodents intended as reptile food – refrigeration and cold water.  Microwave defrosting has certain drawbacks and should be avoided (please see below).
Shared by Flickr user Soregasim

Frozen rodents purchased from a store or breeder should be re-packaged in clean zip-loc bags before being placed into your refrigerator, freezer or sink.  Bowls into which these bags are placed (for warming or cold-water thawing, see below) should be reserved for that purpose…do not use bowls that will also hold your own food, even if the rodents are in clean bags.  My apologies if this seems obvious, but I am continually amazed at how many people place their health in jeopardy while attempting to care for their pets!


Thawing Mice and Rats in a Refrigerator

Thawing under refrigeration is the method of choice in professional collections.  It requires a bit of forethought, but is very safe and requires no effort on our part (other than moving the food item from freezer to refrigerator!).


Thawing time will vary in accordance with refrigeration temperature (usually 35-40 F).  The USDA uses 8-10 hours per 1 pound of meat as a general guideline; a mouse can be expected to thaw in 2 hours, a rat in 4-5 hours.


Fail safe rule: place frozen rodents in a refrigerator for overnight thawing and use them the following day.


Thawing in Cold Water

This method is faster than via refrigeration, but requires periodic water changes, and leaves more room for error.  Frozen rodents in zip-lock bags are placed in a bucket of cold water for 30 minutes, after which time the water is dumped and replaced.  An adult rat can be thawed in as little as 1 hour.


The bags used should be leak-proof, lest harmful bacteria begin to colonize the food item.


Warming and Using Thawed Rodents

After thawing, rodents must be warmed somewhat before being fed to pet reptiles.  This is best done by placing the bagged, thawed rodent in a bucket or other container of warm water.  Timing varies, but plan on 10-20 minutes for a mouse in warm but not hot-to-the-touch water.


Use rodents shortly after thawing and warming.  Whole animals contain internal organs, previously-consumed food, and unpassed wastes, and they decay rapidly.


Common Mistakes

Do not thaw rodents at room temperature or in hot water (this applies to our own food as well).  Bacteria associated with disease and decay, which can be assumed present in all rodents, begin to reproduce at 40 F.  Such bacteria can take hold on the thawed, outer surfaces of a food item despite the fact that its center is frozen.


Rodents should never be thawed in microwaves used for your own food.  Thawing in a microwave reserved specifically for pet food is possible, assuming one can ascertain that the food item is completely thawed yet not partially cooked.


Rodents thawed under refrigeration can be re-frozen (if they have remained refrigerated).  Rodents thawed in cold water should not be re-frozen.



  1. avatar

    I have a Kingsnake, and I bought a frozen mouse for it. Well, I planned on going straight home, but alas my parent had a different plan and drove around for a little while. Well, it’s hot where I live (90° high today) and the mouse was in the car the entire time. If it is partially thawed from the outside heat then defrosted the rest of the way in warm water, is it still safe to feed him it?
    Thank you!

    • avatar

      Hello Christy,

      I can’t be sure, as I’ve not had any experience with that situation…you’d need to discard food meant for people if it had been thawed in that way, due to some peculiarities in the way bacteria grow …I would err on the side of caution and discard it…missing a meal will never harm a snake, don’t worry! Best, Frank

  2. avatar

    So I thawed some mice out in the fridge last nigh, and this morning my snake went full opaque. She’ll probably shed in 2-3 days (I got her two months ago and it’s still hard for me to tell when she’s going into shed before her eyes become opaque).

    So my question is, how long can the mice stay in the fridge before they should be thrown out? (I hate refreezing mice).

    • avatar

      Hello Cree,

      Yes, best not to re-freeze. Due to presence of internal organs, food in gut, mice do not keep well in the frig – at the zoo, we discard after 1-2 days. Best, Frank

  3. avatar

    Hi I have a sinaloan milk snake for 12 years now and was wondering how long their life span is. I have read 10 – 12 years and 15-17 years and is their anything Special I need to do for her?

  4. avatar

    I have been told a few conflicting things that I want to know the truth about, but feel stupid to ask at the local pet store that I shop at!

    (Just for conversation sake so you know about the animals I’m carrying for, I have two young female ghost pythons!)

    First thing is I have been told that if a snake is kept in a large enclosure that they will grow larger and someone else told me that they will get the same size no matter what.

    I’ve also been told to feed the maximum size mouse ( bring careful that the size won’t choke them) and then feeding an additional smaller mouse with it to give them extra food/protein to increase their growth potential and then I was told that this wouldn’t make them grow more.

    I was told about some drops to add to their water so you can use tap water and was told I wouldn’t need it if I use filtered water and then someone else told me I need it no matter what.

    One person told me to wait 24 hours after feeding them before holding them someone else told me 48 hours and then another person told me it depends on the snake and they can be handled after they start moving around more.

    I was told to only feed frozen mice because live ones can hurt the snake and then the lady at the pet store said that isn’t necessary just to watch the feeding and make sure they are safe.

    I’ve only had them for a few days and tonight is their first feeding at home! Please include any other information you think would be useful!

    • avatar

      Hi snakie mom! I hope to answer some of your questions, and I’m sure others can chime in. An enclosure should be large enough for any animal to grow. This doesn’t necessarily enhance growth (makes your pets grow faster, larger, etc), but it does prevent retarding the animals growth by having them in a smaller enclosure. Any animal will grow to their natural size, unless something prevents them from doing so. So, the larger the better!

      The best rule of thumb for feeders is the feeder rodent should be 1 to 1 1/2 times the diameter of your snake’s middle. One feeder per snake is all you need, and if they are adults you should only be feeding them once a week (every 5 days if they are still babies).

      Drops never hurt as most reptile safe drops hold additional vitamins, but it is not a necessity as the nutrients come mostly from the food and light source. A healthy snake is a happy snake. If you are interested in drops for your water, then we recommend Reptisafe http://www.thatpetplace.com/zoo-med-reptisafe

      With holding them, we would recommend 48 hours to do so. Some snakes are nervous eaters and can still regurgitate their food prior to that, which is very harmful to a snake.

      You can feed live mice without any issue, they off course eat them live in the wild 🙂 If you are feeding a frozen, they should be properly thawed, and you should shake them about (give them movement) with a feeding tong until your snakes latch onto them. Once they are latched, watching the snake feed isn’t a necessity. Worse case scenario a feeder might scratch you snake, so we would recommend watching until the snake has latched. Checking in on them during the feeding wouldn’t hurt, but you certainly don’t have to sit and watch.

      Here are some additional articles that you might want to check out;

About Frank Indiviglio

Read other posts by

Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
Scroll To Top